In the course of study of inborn errors of metabolism, we have encountered four patients with Kinky hair disease, a rare sublethal disorder. The condition was presumed to be caused by absorptive defect of copper but the extent of the deficit was not known. Using intravenous and oral administration of labelled 67Cu to the same patients, we demonstrated the extent of absorptive defect of copper to be in the range of 11-13 per cent. These patients retain the absorbed or infused copper 3-4 times longer than unaffected controls. Subsequently, we have modified the method of parenteral administration of copper by using subcutaneous infusion in low concentration to permit long range ambulatory therapy in young infants.